The present invention relates generally to the field of reducing audio feedback in microphones and more particularly to reducing the audio feedback using an auxiliary vowel detection sensor and a monotonic volume detector.
Microphones are an acoustic to electric transducers or sensors which converts sound in air into an electrical signal. Microphones are used in many different applications from telephones, hearing aids, public address systems for concert halls and studios, speech recognition, and many other applications. Most microphones today use electromagnetic induction, capacitance change, or piezoelectricity to produce an electrical signal from air pressure variations. The microphone typically needs to be connected to a preamplifier before the electrical signal can be amplified with an audio power amplifier or recorded.
A common occurrence when a microphone is connected to an amplifier, is audio feedback. The feedback is occurs when a sound loop exists between an audio input (for example, a microphone) and an audio output (for example a speaker). A situation where the feedback occurs is when an audio signal received by the audio input is amplified and passed out of the audio output. The sound from the audio output is received by the audio input again, amplified further, and passes through the audio output again. The frequency of the resulting sound is determined by many different factors, but the result is similar in the audio output making a loud squeal, whistle, or screech noise (referred to as feedback).